Fuel for competition and recovery!

Hydration techniques used to enhance performance and recovery including water; hypertonic, hypotonic and isotonic sports drinks; and intravenous rehydration

Nutritional strategies used to enhance performance and improve recovery including carbohydrate loading, application of the glycaemic index, carbohydrate gels, and protein supplementation

What can cause fatigue in an athlete?

depletion of glycogen stores

hypoglycaemia (low blood-glucose levels)

dehydration

low blood-sodium levels

gastrointestinal upset.

Fuelling for shorter-duration sports

Less than 60 min

No glycogen depletion = no need to refuel during the event.

Glycogen stores should be adequate before and after training and competition.

Fluid replacement will need to happen, water is adequate, however sports drinks are more tasty!

Fuelling for moderate intensity or intermittent sports

60-90 minutes

Can normally be fuelled by gycogen stores in athletes.

Tapering of training and carbohydrate consumption of 7-10 grams per kg in the 24-36 hours prior to the competition

Fuelling for prolonged sub-maximal events

Longer than 90 minutes e.g marathon

Endurance athletes already have a higher amount of glycogen stored.

They can also consume additional carbohydrate before the event = Carbohydrate Loading.

Carbohydrate loading can increase stores of muscle glycogen 50-100% above normal resting levels.

Carb loading + tapering = increased muscle glycogen stores.

During the event 30-60 grams of carbohydrates per hour schould be consumed

Extra reading: “What is carbohydrate loading?” page 358

Pre-event meal and fluid requirements

The major goals of the pre-event meal are to:

finish topping up glycogen stores (especially in the liver, because they will have depleted overnight)

top up fluid levels

leave the gastrointestinal system comfortable during the event

prevent hunger

Pre event meal

Ideal timing = 1-4 hours before the event.

3-4 hours before consume a meal

or

1-2 hours before consume a light snack

Foods with a Low GI , low in fat and moderate in fibre and protein.

Suitable foods

Foods suitable 3–4 hours prior to exercise include: breakfast cereal with milk baked beans on toast bread roll with cheese or meat filling and a banana pasta or rice with a sauce based on low-fat ingredients (i.e.

tomatoes, vegetables, lean meat).

Snacks suitable 1–2 hours prior to exercise include: milkshake or fruit smoothie sports bar fruit-flavoured yoghurt fruit.

Low Gi foods are not beneficial during exercise.

Refuelling during exercise

Sports lasting 60-90 minutes can be fuelled by stored carbs and fats without the need to replenish during the event.

Sports that last longer than 90 mins may benefit from consumption of carbohydrates as fuel fatigue is likely.

How does it help?

Carbohydrate consumption can lead to glycogen sparing by using the carbs to remake glycogen for later use.

Also this keeps blood glucose levels in a normal range providing extra fuel and delaying fatigue.

Recommended starting early in the event 30-60 grams of moderate to high GI foods per hour.

E.g 60 grams carbs = two bananas or 95 grams jelly beans

Type of exercise Refuelling suggestion

Intermittent team sports lasting 60–90 minutes

•Recent studies have found that intermittent team sports may benefit from consumption of carbohydrate during the game as it is said to delay fatigue, prevent low blood-glucose levels and promote glycogen sparing.

Type of exercise Refuelling suggestion

Endurance events > 90 minutes

•As there is no indefinite supply of glycogen within the muscles or liver, carbohydrate refuelling is advised at a rate of approximately 30–60 grams per hour, or 500–1000 mL of a sports drink, or 10–20 jelly beans. (This is dependent on the individual athlete and will be determined following specific experimentation and consideration of environmental factors such as heat.)•Sports drinks, bananas, sports bars or sugar confectionery such as jelly beans are highly recommended, although ultimately it is the choice of the athlete as to which foods are most comfortable to ingest while competing.

Type of exercise Refuelling suggestion

Ultra-endurance events > 4 hours

•Typically these athletes compete at a lower intensity than most team sports or short-distance events. This allows digestion to take place while competing, so the athlete can consume small amounts of solid foods.•High-carbohydrate foods, in conjunction with small amounts of protein and fat, are advised for the ultra-endurance athlete. Muesli bars, sports or breakfast bars and jam sandwiches are a good choice for ingestion during performance.•Obviously hydration must also be addressed throughout the event. Carbohydration is beneficial in these events as well.

Recovery

As previsously discussed

Studies have shown that an athlete should consume carbohydrate-rich foods and drinks that provide at least 1 gram of carbohydrate for each kilogram of body mass within 30 minutes after exercise.

Extra reading : Getting the timing right

YOUR TURN!

List the factors that can cause nutrition-related fatigue in an athlete.

Compare the differences in fuelling for events of differing durations.

YOUR TURN!

Define carbohydrate loading. Is it a suitable strategy for all events? Explain.

Explain the function of the pre-event meal.

Discuss how long before competition a pre-event meal should be consumed.

With reference to the glycaemic index, identify the types of foods that should be consumed pre event, during the event and post event.

Identify the duration of event for which consumption of small amounts of solid food during competition is recommended. Explain why this is recommended.

10.5 Hydration

More than half your body weight and over 70 per cent of your body mass is water. Each day the body needs to replace about 2 litres of fluid to balance what is lost (and this is not even accounting for fluid loss through sweating!).

Functions of fluid

to transport energy, waste, hormones and antibodies

to dilute waste products

to lubricate surfaces and membranes

to help regulate body temperature

to be involved in all chemical reactions in the body.

How much fluid?

200-600 mL of fluid prior to their event

500-1000mL of fluid per hour of activity.

Replacing fluids is vital as we can lose up to 6L or 3-4kg due to sweat and other mechanisms

We can assess how much fluid we need to consume by doing pre and post competition weigh ins.

150% of the fluid lost should be consumed i2 2-4 hours. If athlete loses 2kg then they need to drink 2-3L of fluid to rehydrate.

Extra reading “fluid who needs it?” page 365

Water vs Sports drinks

Sports drinks such as Gatorade, Isosport, Powerade, Lucozade and Endura are popular means of replenishing fluid losses.

There are 3 different types of sports drinks

Type Content

IsotonicFluid, 6–8 per cent carbohydrate, 10–25 mmol/L electrolytes (e.g. Gatorade)

HypotonicFluid, low level of carbohydrate (< 8 per cent), 1–25 mmol/L electrolytes (e.g. water)

HypertonicFluid, high level of carbohydrate (> 8 per cent) (e.g. fruit juice, soft drink)

Isotonic sports drinks

Most widely used.

Advantages are Carbs and electrolytes provide taste and helps

stimulate consumption. Sodium aids in the retention of consumed fluids

within the body without bringing on thirst. The carbohydrates aids in energy replenishment

Hypotonic sports drinks

Act quickly to replace fluids lost through sweating.

Less carbs so absorbed more quickly.

Good for jockeys.

Hypertonic sports drinks

Used during and after prolonged endurance and ultra-distance events.

High carb levels so absorbed slowly

Need to be used with isotonic drinks to replace fluid loss

Sports water

Good alternative to plain water. No research done yet

Extra reading : Aussie athletes cool off with a slushie page 368

Intravenous drips in rehydration

For many years, intravenous (IV) hydration has been used in sport to medically assist athletes suffering from severe dehydration. Now used for recovery

Justine Henin-Hardenne won the US open tennis after using an IV drip the night before to reverse the dehydration she suffered during her three hour pervious match.

Brisbane lions used IV drips at halftime to rehydrate players.

IV infusions are now in the banned list of substances inless medically required

YOUR TURN!

State how much fluid sports dietitians recommend an athlete should consume before, during and after an exercise session.

Describe how you can check if you are taking in enough fluid.

Explain the difference between each of the three types of sports drinks.

Explain the underlying rationale behind the use of IV drips as a means of rehydrating athletes after competition or training.

For each of the following people, suggest what type of hydration would be best.

Mum who walks for 30 minutes with pram around local creek to maintain weight and fitness.

Local footballer who goes to the gym four times a week to work on his strength and power via a weights program. He has a snack before each session and sips water throughout.

Elite netballer who trains five times a week, completing individual cardio sessions (i.e. running) or specified team training sessions. She also plays competitively once a week.

Weight-lifter who trains every day but needs to monitor weight prior to competition.